1. Field of the Invention
This invention relates to a flow rate and volume sensor for determining the rate and volume of fluid flowing through an apparatus, such as an apparatus for filtering and/or conditioning and/or purifying fluid, such as water, and for indicating when a predetermined volume of fluid has flowed through the apparatus to, for example, signal when a cartridge filter housed in an apparatus for filtering and/or conditioning and/or purifying fluid should be replaced.
2. Description of the Prior Art
Filtration apparatuses and purification apparatuses comprising pressure vessels that hold cartridge filters or the like for filtering and/or conditioning and/or purifying fluid (for example, water) are used in residential drinking water systems, boats, recreational vehicles, aircraft, and vending machines. The cartridge filter, or the like, used in the pressure vessel for filtering and/or conditioning and/or purifying fluid removes contaminants from the fluid as the fluid flows through the cartridge filter, or the like, thereby filtering and/or conditioning and/or purifying the fluid. The cartridge filter, or the like, has a specific lifespan for filtering and/or conditioning and/or purifying fluid, and at the end of the lifespan, the cartridge filter, or the like, should be replaced with a fresh cartridge filter, or the like, in order to continue to effectively remove contaminants from the fluid flowing through the pressure vessel. Failure to replace a cartridge filter, or the like, after the cartridge filter, or the like, has been spent may possibly lead to contaminants not being removed from the fluid by the spent cartridge filter or the like, which may lead to hazardous situations. For example, when the fluid is water, contaminants may remain in the water after passing through the spent cartridge filter, or the like, and when such water having unremoved contaminants therein is consumed, health hazards may occur.
With some filtration apparatuses and purification apparatuses, after a certain amount of fluid has been filtered and/or conditioned and/or purified, the cartridge filter or the like becomes clogged with contaminants and therefore spent. A reduction in or slowing down of the normal flow rate of filtered/conditioned/purified fluid from the filtration apparatus or the purification apparatus indicates that the cartridge filter or the like has become clogged With contaminants and needs to be replaced.
Various attempts have been made to provide an indication for when a cartridge filter or the like should be replaced with a fresh cartridge filter or the like in place of merely waiting for the cartridge filter or the like to become clogged and the flow rate therethrough reduced to an unacceptable rate. For example, a known water filtration apparatus has a flow indicator that senses water flow and indicates that water flow is taking place.
Another known water filtration apparatus senses water flow and assumes a flow rate to calculate an estimated total flow of water through the water purifier. This known water filtration apparatus is complicated and only produces an estimated total flow, which leads to the cartridge filter being replaced prematurely if the actual flow rate used is typically lower than the assumed flow rate and to the cartridge filter being replaced well past the recommended life of the cartridge filter if the actual flow rate is typically higher than the assumed flow rate.
Another known water filtration apparatus uses a timer to determine when it is time to replace the cartridge filter. Because replacement of the cartridge filter is determined by time rather than by usage of the water filtration apparatus, replacement of the cartridge filter may be called for prematurely when the water filtration apparatus is not regularly used or replacement of the cartridge filter may be called for well beyond the recommended life of the cartridge filter when the water filtration apparatus is used a lot.
However, it would be desirable to provide a flow sensor that indicates when a cartridge filter or the like should be replaced based on the actual amount of fluid flow that the cartridge filter or the like has been designed to filter and/or condition and/or purify, rather than a possibly inaccurate estimated amount of fluid flow.